As the above-mentioned motion guide device, there has been known a motion guide device as disclosed in JP 59-166022 U. This motion guide device includes a track rail having a rolling surface for rolling elements, and a guide body assembled to the track rail through intermediation of a large number of the rolling elements in a freely movable manner. The rolling elements roll under a load between the rolling surface of the track rail and a rolling surface on the guide body side. With this, the guide body can be moved along the track rail. Such motion guide devices are utilized mainly, for example, in a linear guide portion of a working machine. The motion guide devices for such uses are required to have high load bearing capability, and to guide objects with high accuracy.
Thus, in the related-art motion guide devices, the rolling surfaces of the track rail and the guide body on which the rolling elements roll need to be formed by a grinding process in a unit of μm, and a quenching process needs to be executed on steel to be formed into the track rail and the guide body so that the rolling surfaces have higher durability and higher load bearing property. Such processes increase production cost of the motion guide devices.